Synthesis,Characterization And Performance Of Guanidinium Pentazolate

Pentazole,the final member of the azole series,has been considered as a key candidate for high-energy materials.Pentazole has the advantages of good oxygen balance,high enthalpy of formation,huge energy release and high specific impulse,which is expected to achieve amazing results in the field of propellants and explosives.Therefore,the potential applications of pentazole compounds as high energy density materials have received increasing attention.Based on the advantages of pentazole anions and guanidine cations in the field of energetic materials,the diaminoguanidinium pentazolate salt and traminoguanidinium pentazolate salt were synthesized with the high nitrogen content more than 85%.The paper investigated the effects of the substituent effect,solvent effect,and oxidant effect on the decomposition of arylpentazole and C-N bond cleavage.It was found that the action of ferrous glycine on arylpentazole could cause the benzene ring to form a quinone structure with oxygen-containing groups,which was beneficial to the cleavage of C-N bonds.And the study found that the para-hydroxyl group is the most favorable oxygen-containing group for cutting reaction.The target compound guanidinium pentazolate salts were characterized by mass spectrometry,infrared spectroscopy,and nuclear magnetic resonance.It was determined that the prepared guanidinium pentazolate salts had the high levels of salt purity without futher purification.Using single crystal X-ray diffraction,the molecular structure,anion-cation interaction rule and spatial arrangement rule were further determined.Their crystal structure analysis showed that the diaminoguanidinium pentazolate salt crystal belongs to the triclinic crystal system with P-1 space group,and the traminoguanidinium pentazolate salt crystal belongs to the Orthorhombic crystal system with Pmna space group.Quantum theoretical calculations show that both the anions and cations of the guanidinium pentazolate salts have high flatness.There are a variety of hydrogen bonds with different strengths in the molecule and between the molecules,and the existence of a large number of ?-? interactions between the molecular layers are responsible for their high density.By analyzing the Hirshfeld surface,the 2D fingerprint,and the percentage contribution of the Hirshfeld surface,it was found that the strong ?-? interaction in the C-N bond of the guanidinium pentazolate salt results in lower sensitivity.Thermal gravimetric-differential scanning calorimetry and surface electrostatic potential(ESP)analysis of the thermal stability revealed that the initial decomposition temperatures of the pentazolidine salt could reach 93.9 ? and 97.2 ?,respectively.Finally,the Guassian 09 package was used to calculate the enthalpy of formation,the EXPLO5 program was used to calculate the explosion performance,and the standard BAM method was applied to measure the sensitivity(IS and FS).The comparison of the calculation results demonstrated that the guanidine pentazolate salt had better performance in terms of density and decomposition temperature.The performance in terms of detonation speed and pressure has approached the requirements of high-energy-density materials;its enthalpy of formation is more than twice that of CL-20;and it has been found to have lower sensitivity through IS and FS tests.In conclusion,as a novel type of ionic salt,guanidine pentazolate salts have potential research significance for its structure and performance characteristics.